Automatic burner sequencing control system for multi-burner steam generator



June 29, 1965 J. A. SCHUSS ETAL 3,191,558

AUTOMATIC BURNER SEQUENCING CONTROL SYSTEM FOR MULTI-BURNER STEAM GENERATOR 5 Sheets-Sheet 1 Filed Nov. 6, 1962 FIG?) INVENTORS: JACK A. SCHUSS VIRGINIUS Z. CARACRISTI W 4 00M ATTORNEY J n 1955. J. A. SCHUSS ETAL AUTOMATIC BURNER SEQUENCING CONTROL SYSTEM FOR MULTI-BURNER STEAM GENERATOR Filed Nov. 6, 1962 5 Sheets-Sheet 2 FIG.5

FIGQ6 INVENTORS: JACK A. SCHUSS BY VIRGINIUS Z. CARACRISTI Woo? ATTORNEY June 1965 J. A. SCHUSS ETAL 3,191,553

, AUTOMATIC BURNER SEQUENCING' CONTROL SYSTEM FOR MULTI-BURNER STEAM GENERATOR Filed Nov. 6, 1962 5 Sheets-Sheet 5 INVENTORs: JACK A. SCHUSS VIRGINIUS Z. CARACRISTI WJCZM ATTORNEY June 29, 1965 J. A. SCHUSS ETAL AUTOMATIC BURNER SEQUENCING CONTROL SYSTEM FOR MULTI-BURNER STEAM GENERATOR 5 Sheets-Sheet 5 Filed NOV. 6, 1962 2265 Z- OPFDIw 19220- O. A

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vfizsuuu Cut E200 PPA .52 2523. ch Q iii INVENTORS. JACK A. SCHUSS BY VlRGlNIUS Z. CARACRISTI ATTORNEY mm a) s q W w 1* Tr w r Kw m m 5 $5 $33 3: Q5 3 1 \WQQ IQQ $3 \QQ $3 H-- W :QJU -1 HUM: L L 1 11 1 2 mm: 12?? m1 \r \f \f \f \f \.f Kr M v m M W m M w QM United States Patent 3,191,658 AUTOMATIC BURNER SEQUENCENG CON- TROL SYSTEM FOR MULTI-BURNER STEAM GENERATOR Jack A. Schuss and Virginius Z. Caracristi, Hartford, Conn, assignors to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Nov. 6, 1962, Ser. No. 235,704 Claims. (Cl. 15828) The present invention relates to a novel method and apparatus for controlling the fuel burners of a vapor generator. More particularly, the invention relates to an improved method and apparatus for automatically controlling the sequential ignition and shutdown of a plurality of fuel burners in a vapor generator of twin-furnace construction.

= In large vapor generators in which fuel is burned by a plurality of burners, it is desirable to ignite and shut down each of the burners according to a predetermined sequence so that the admission or cessation of fuel and heat to the furnace will occur at a gradual rate in order to prevent the application of shock to the furnace which could conceivably achieve such magnitude that damage to the generator would result. In the past burners have been sequenced by having the operators manually actuate switches in a sequenced order, but current technology has permitted such burners to be sequenced automatically by means of control systems which actuate each of the components of the burner system in sequence thereby obviating the need for manual firing and thus eliminating the danger of human error.

Heretofore, such control systems have embodied cams, timers, and other various actuating means to actuate the burners according to a predetermined pattern or sequence. They have largely reduced the element of human error but because of the addition of these special sequencing apparatus,'there remains the ever present danger of breakdown of the control system due to the complex nature thereof. This complexity understandably reduces the reliability of the systems because, for a control system to operate correctly, all of its components must function properly, and in such systems the large number of parts which must function properly increases the danger of having one of the parts not function thereby destroying the operability of the entire system.

The present invention provides an improved control system for controlling the operation of a burner system in which the special additional timing devices to achieve a sequenced operation of the burners have been eliminated thereby eliminating a potential cause of system breakdown and thereby increasing the reliability of the automated burner system. The aforesaid is brought about by utilizing the characteristics of the burner components themselves to achieve the effects heretofore brought about by special components whose function it was to operate the burner components in sequence.

The elements which make up the present control system are arranged to automaticallyignite and shut down an elevation of burners in a large vapor generator of twin furnace construction. The burners are ignited and shut down in a manner which insures a balance of heat in each of the furnace sections. Moreover, means are provided which permits ignition of the individual burners only when they are capable of operating properly and other means are provided to isolate an inoperative burner from the remainder of the burners in the elevation so that an entire elevation of burners need not be rendered inoperative merely because of the inability of one of the burners to function.

It is there-fore an object of the present invention to Patented June 29, 1965 ice provide a method and apparatus for sequencing the ignition and shutdown of the several components of a burner system comprised of a plurality of fuel burners which is structurally simple yet operably reliable.

Another object of the invention is to provide a control system for the burner system of a twin-furnace vapor generator wherein the burners in each furnace are ignited and shut down in sequence by means of a pair of actuating signals which traverse the burner system in opposite directions, one of which is capable of completing the ignition or shutdown of the entire burner system if, perchance, the other signal is prevented from traversing its assigned portion of the system.

Still another object of the invention is to provide a control system for a plurality of burners in a vapor generator which utilizes the functions of each of the existing components of a conventional burner system to actuate the other components of the system in sequence thereby eliminating the necessity of adding elements to the system in order to effect sequential actuation of the various burner components.

Yet another object of the present invention is to provide a method and apparatus for controlling the sequenced actuation of the several components of a multi-burner fuel burner system which permits an alternative routing of the actuating signal upon the malfunctioning of one of the burner system components which would normally prevent continuation of the actuating signal for the remaining burners in the system and thus isolate the inoperative burner while permitting the sequencing burners to continue in an orderly fashion.

With the foregoing and other objects in view, the invention comprises the novel method of operating a burner system and a control system therefor hereinafter more fully described and illustrated in the accompanying drawings wherein:

FIGURE 1 represents a schematic showing of one type of vapor generator utilizing the present invention;

. FIGURE 2 is a section taken along line 22 of FIG URE 1;

FIGURE 3 is a schematic illustration of the sequence followed by the burners shown in FIGURE 1 in starting up and shutting down;

FIGURE 4 is a diagrammatic representation of the fuel supply system feeding each of the burners of the present burner system when gas is employed as the heating medium;

FIGURE 5 is a diagrammatic representation of the fuel supply system feeding each of the burners of the present burner system when oil is employed as the heating medium;

FIGURE 6 is a schematic representation of one form of fuel valve employed in the present system;

FIGURE 7 is a schematic representation of another form of fuel valve employed in the present system;

FIGURE 8 is a circuit diagram of a control system employed to obtain the sequenced ignition of a gas burner system according to the present invention;

FIGURE 9 is a circuit diagram of a control system employed to obtain the sequenced ignition of an oil burner system according to the present invention;

FIGURE 10 is a circuit diagram of a control system employed to obtain the sequenced shutdown of an oil burner system according to the presentinvention;

FIGURE 11 is a schematic representation of one of the relays employed in the control system shown in FIG- URE 8;

FIGURE 12, is a schematic representation of another relay employed in the control system shown in FIG- URE 8;

FIGURE 13 is a schematic representation of one of the relays employed in the control system shown in FIG- URE 10.

FIGURE 14 is a schematic representation of another relay employed in the control system shown in FIG- URE 10.

Referring now to the drawings, FIGURE 1 shows a vapor generator 18 having two furnace cavities 12 and 14. These cavities may be considered as having outer walls lined with upright vapor generating and wall cooling tubes 16. The cavities 12 and 14 include a common wall or partition 18 formed of similar tubes. The tubes 16 lining the outer walls of the furnace as well as those forming the partition 18 are connected at their lower ends and their upper ends with appropriate headers, the upper headers 20 being connected by riser tubes 22 to a vapor and liquid drum 24. The drum 24- is connected by downcomers (not shown) to the lower headers 26 so as to complete a fluid path through the unit.

Each of the furnace cavities 12 and 14- is provided with a system of fuel burners which supply heat to the unit to transform the fluid flowing through the tubes 16 into vapor. The generator shown in FIGURE 1 is arranged to accommodate a burner system employing three burner elevations 28, 30 and 32 of eight burners each or a total of twenty-four burners. Each elevation of burners is equipped with its own sequencing control system in accordance with the present invention so that the individual elevations can be individually or cumulatively fired depending upon the load requirements of the generator.

As best shown in FIGURE '2, the burners of each elevation are located at the corners of the furnace and are associated therewith to effect tangential firing. For the sake of clarity, the corners in furnace cavity 12 have been indicated'as A, B, C and D and those in cavity 14 indicated as E, F, G and H.

The burner system contemplated by this invention can employ gas, oil, or both as the heating medium; however, different fluid systems and therefore different control systems, must be employed for each type of fuel used. FIG- URE 4 shows a typical piping diagram for the fuel system of a single burner when gas is employed as the heating medium. The arrangement is the same for each of the eight burners in each burner elevation and for the sake of avoiding repetition only the system for a single burner is described here. As shown, each burner assembly consists of a burner nozzle 34 which is connected to a gas supply source, here shown as a header 36, by means of a conduit 38. The supply source is common to all of the burners in thehurner system. Interposed in the conduit 38 between the nozzle 34 and the header 3d are a pair of valves indicated in the figure as it and 41. Valve 40 is an automatic supply valve. that is positioned in the line 38 to admit gas from the source 36 to the burners 34 and valve 41 is a cock valve operable to selectively isolate the burners from the remainder of the system.

Valve 40 is a slow opening but rapid closing valve which permits the gradual increase of fuel from zero to rated flow upon opening and an abrupt cessation of flow upon shutdown. Gradual introduction of fuel to the furnace is required in order to prevent subjecting the furnace chamber to an undesirable pressure shock upon ignition.

In order to effect valve operation in this manner, the preferred embodiment of the invention employs a valve 4-6 having an electro-hydraulic operator 39. Such a valve is shown in FIGURE 6 and comprises a valve body 42 having an inlet 43 and an outlet 44. Within the body 4221 valve plug is operated to slowly permit passage of fuel through the line 38. -To effect this slow passage of fuel, the valve plug is connected to a hydraulically actuated piston 50 by means of valve stem 48 and operates against the force of a spring 52. Fluid is supplied to the underside of the piston 50 through inlet line 54 by means of a pump 55 which is driven by an electric motor 55. A normally closed limit switch S8 is provided which effects cessation of the operation of motor 55 once the valve 46 reaches its fully open position. This switch 53 is actuated to an open position by means of a lug 57 attached to the valve stem 48. A second, normally open, limit switch 62 is also provided and is actuated to its closed position at the same time as the limit switch 58 is opened by means of a similar lug. This latter switch 62 is connected to an electro-magnetic relay 140 which effects actuation of a similar fuel valve associated with another burner in a manner which will be described in detail hereinafter.

Even after deactuation of the motor 55, fluid pressure remains within the actuator cylinder 51 until an internal relief valve 60 is opened by means of a solenoid 61 thereby releasing the fluid beneath the piston 5t? and permitting the valve plug to become seated within the valve body 42. Valve closure is augmented by the force of the spring 52 which operates against the top side of the piston 50 to seat the valve plug very rapidly.

In accordance with the present invention, means are provided to automatically actuate the components of the burners in each furnace elevation such that the ignition of each elevation progresses in a sequenced manner. The manner in which sequencing occurs is represented by the diagram shown in FIGURE 3 wherein 12 and 14 represent each of the furnace cavities in the generator and A, B, C, D, E, F, G and H represent the location of each of the burners in the corners-of the cavities. Orderly ignition of the burners proceeds as follows, the progression being represented by the solid line in the figure. First, the burners at corners A and F are simultaneously lighted. Burner A, in cavity 12, after its ignition which requires a short period of time, then effects the start of ignition of burner H in cavity 14 and similarly, burner F in cavity 14 begins the ignition process of burner C in cavity 12. Burners H and C, upon the ignition, thereafter effect ignition of burners B and E respectively in a similar fashion, and this is followed by ignition of burners G and D which completes the ignition of the entire elevation.

With burner pairs, one burner located in each cavity, being ignited simultaneously, the arrangement is such that a heat balance is maintained between the cavities thereby preventing one cavity from receiving an appreciably greater amount of heat than the other cavity. On the other hand, the ignition of burners in alternate furnace cavities is also desirable in order to maintain this heat balance between cavities when the burner ignition is conducted by means of the alternative manner of firing which is incorporated into the system and which is employed when, for some reason, one of the burners in the system is rendered inoperative thereby preventing the sequence progression from continuing along one of the routes shown in FIGURE 3 as AHBG or F-CED.

This alternative routing ofthe ignition signal is represented by the broken lines in FIGURE 3. It is employed when the sequence cannot continue along route F-C-E-D, for example, because the operator for burner C, we assume, has failed to function thereby preventing a continuation of the signal from C to E and then to D. When this occurs, the present control system provides means to permit the signal which is traversing line A-H-B-G, to

7 continue on to burner D after burner G is operating thereby lighting off this burner which, in turn, will ignite burner E, burner Cs ignition being prevented due to the burners inoperativeness.

The control system employed to achieve the aforementioned function is shown schematically in the wiring diagram of FIGURE 8. Lines 120 and 122 are the live and :ground leads respectively from a volt, 60 cycle, single phase source of electric power. Connected in parallel across these lines are a plurality of lines in which are located the contacts of the various switches used to effect the sequenced operation of the burner system.

Each burner has associated therewith a pair of parallel lines which are indicated as lines 124 and 126 followed by the appropriate suifix for the burner with which they are associated. Connected in series along lines 124 are a number of contacts which are associated with normally 'open switches indicated as 123, 138,132 and 134.

Switches 128, 130 and 132 are, in fact, associated with safety means which permit actuation of the burners only after predetermined conditions have been satisfied. Switch 128 is connected to a pressure sensing device which actuates the switches 128 in all of the lines 124 after a predetermined pressure is exhibited in the gas supply source 36, a relay 129 being actuated to close the contacts in the lines simultaneously. Switches 130 are similarly closed by a relay 131 which is actuated upon receipt of a signal from a computer or from a normally operated ignition start switch. Switches 132 are connected to differential pressure sensing means associated with each burner which determine that the igniter associated with each burner is operating. Switches 134 are associated with the cock valves 41 in the gas supply lines 38 and are closed when the cock valve is in an open position. The purpose of these latter switches is to permit the burners to be selectively isolated from the burner system when it is desired to service the fuel line or any of the components of the associated burner.

Switches 58 are limit switches shown in FIGURE 6 associated with the supply valve operators 39. These switches are normally closed and maintain power to the actuator pump motor 55 until the valve 40 is opened. When the valve is fully open, the switch 58 is actuated to its open position thereby stopping the operation of the pump motor 55. However, this motor stoppage does not effect a closure of the valve until the solenoid 61 is actuated to open the relief valve 60.

Lines 126, which are connected in parallel with lines 124, contain normally open limit switches 62 associated with the supply valve 46 which are closed when the supply valve reaches its full open position. Also contained in lines 126 are electro-rnagnetic relays 140 and 141 (FIG- URES 11 and 12) which are actuated upon closure of the switches 62. These relays have a plurality of contact points which are connected to the various ancillary apparatus associated with each of the burners, such as the control panel lights which indicate .that the supply valves 40 are fully open, the burner counting circuit which insures that a suflicient number of burners are ignited to generate sufficient steam to satisfy the load requirements of the generator unit, the feedback signals to the computer to indicate that the valve is open, and several other elements which are not materially germane to the present invention.

As shown in FIGURES 11 and 12, the relays 140 and 141 also effect closure of switches 136 located in lines 124 associated with the following burner in the sequence progression. It will be noted that switch 136 does not appear in lines 126A or 126F since these lines are associated with the initiating corners of the furnace and receive the actuating signal from the computer or start switch and not from a relay associated-with one of the other burners in the system. Relay 141 (FIGURE 12) additionally contains contacts, which efi'ect closure of switches 138 in lines 124 associated with an anterior burner, or one which would normally be ignited previously in the burner sequence. Switches 138 are connected in parallel with switches 136 and provide the means for i the alternative routing of the ignition signal when the switch 136, connected in parallel with each of the switches 138, cannot be closed.

The operation of the control system is as follows. First, the pressure sensing device in the fuel supply source 36 indicates a sufiicient amount of fuel pressure at the source thereby actuating a relay 129 which closes all of the switches 128 in lines 124. The igniter flame sensing device associated with the burners in each of the corners indicates that the associated igniter is operating and closes the appropriate switches 132. Similarly, the cock valves in the various fuel supply lines are open so that switches 134 are closed. Next, the control system receives the start signal from a computer or start switch thereby actuating the relay 131 which closes all of the switches in the system. Closure of the switches 130 thereby effects a complete circuit in lines 124A and IMF but not in any of the remaining lines since switches 136 and 138 still remain open.

When the circuit is completed in lines 124A and 1241*, power is delivered to the motor 55 in the operators 39 for the supply valves 40 associated with burners A and F. When these valves are fully open, burners A and F are receiving rated gas flow which is ignited by the igniters associated with the burners and are, therefore, in full operation. Also, when the valves 40 reach the full open position, switches 62 in lines 126A and 126F are closed thereby actuating the relays 1463A and 14011 Actuation of these relays eifects closure of switches 136 in the lines 124 associated with burners H and C respectively thus establishing a completion of the circuits across lines 124H and 124C. The establishment of power across lines 1241-1 and 124C eflfects actuation of the supply valves 49 associated with the burners Hand C. When the valves 40 associated with burners H and C reach their full open position, switches 62 in lines 12611 and 126C are closed thereby actuating relays 14iH and C, relay 140H closing switch 136B in line 124B and relay 140C closing switch 138E in line 12413 to initiate the ignition process for burners B and E. When burners B and E are in full operation, their associated relays 141 are actuated, and these relays effect closure of the switch 136 associated with the next burner in the sequence progression and also switch 138 associated with the previous burner in the sequence progression. If the previous burner in the progression is already operating, closure of the switch 138 has no effect. However, if for some reason the switch 136 had not been closed and if the other switches 128, 130, 132, and 134 in line 124 were closed meaning that the burner was operable, closure of switch 138 would complete the circuit in line 124 and thereby effect ignition of that burner.

The alternate routing of the ignition signal comes-into play when one of the burners in the burner system is rendered inoperative, either because it has been removed for maintenance purposes and switch 134 remains open or its igniter is not functioning properly and switch 132 remains open. This operation is best described by way of the following example. Assuming that burner C in line F-CED has been rendered inoperative because its igniter was not functioning, and switch 132C could therefore not be closed, relay 140C could not be actuated to close switch 136E thereby preventing the ultimate ignition of burner B when its comparable burner B in line A-HBG was igniting. Under these conditions, burners A and F would be firing, burner A would effect the actuation of burner H, burner H would in turn eifect actuation of burner B and burner B would effect actuation of burner G, the progression now being stopped in line F-C-E-D because burner C was inoperative. Ignition of burner G with its concomitant energization of relay 141G would now effect the closure of switch 138D to close the circuit in line 124D thus permitting the supply valve associated with burner D'to be opened and the burner to commence firing. When burner D is operating, relay 141D is actuated to close switch 138E in line 124E to thereby open the supply valve 40 associated with burner E, and this burner likewise commences firing in sequence. There is thus established complete operation of the burner elevation except for the burner which has been rendered inoperative (C in the present illustration), this burner being isolated and the incomplete burner elevation nonetheless being permitted to operate.

FIGURE 5 discloses the piping arrangement for a single burner of the burner system when oil is used as the fuel. As shown, each burner includes a retractable burner nozzle 80 having a piston 82 mounted thereon. The

Y piston 82 is enclosed by a stationary'cylinder 84 and permits extension and retraction of the burner nozzle 8t into and out of the furnace cavity by means of an air line 86 which connects the cylinder 84} with the extension port 95 of a 4-Way valve 92 and a line 89 which connects the cylinder as with the retraction port 93 of the same valve 92. Extension of the nozzle 1% is effected :by the actuation of a solenoid @4 which permits compressed air to flow through line 86 to the rear side of piston 82 thereby forcing the piston and therefore, the burner'nozzle 8% to its extended position. Retraction of the burner nozzle 80 is effected by actuation of a similar solenoid )6 admitting compressed air through line 3% to the right side of the piston while at the same time opening the vent port 91 to rele-ase'the pressure on the left hand side of the piston thereby permitting the nozzle to move to its retracted position. s

' The nozzle 8% is connected to an oil source of supply, here shown as header 191 by means of conduit 98, a portion of which, indicated as 1%, is formed of flexible ho'sing to accommodate movement of the nozzle. A line 102 is provided to return unburned oil from the nozzle 80 to the source, and also contains a portion, indicated as 104, formed of flexible hosing. A slow opening, rapid closing electro-hydraulic supply valve 1% is positioned in the line 98 to effect gradual admission of oil to the nozzle 86. This valve is similar to the valve 4t described inconjunction with the burner system employing gas shown in FIGURE 6. Another electrohydraulically actuated valve 108 is interposed in the line 1&2 along with the check valve 1&9.

The valve 1% as shown in FIGURE 7 is essentially the same as valves ttt and 106 shown in FIGURE 6 with the exception that its operator 116i is arranged so as to eitect rapid opening but slow closure. To accomplish this the operator 11% is arranged with thefluid inlet line 54- communicating with the cylinder 51' above the piston d and the spring 52 is located so as to force the piston 59 in an upward or opening direction. Thus, actuation of the pump motor 55 admits fluid to'the cylinder 51' in a manner which will serve to close the valve 108 gradually. Wlien it is desired to open the valves, the solenoid 61' is actuatedto open relief valve 669' which vents the fluid from cylinder 51 permitting the piston 5%.? to be forced upwardly its movement being assisted by spring 52'.

When the burner is to be put into operation, solenoid 94is first actuated admitting air through line 86 to the cylinder 34 to extend the nozzle 80 to its operating position. When the nozzle reaches its fully extended position, asindication of such occurrence is effected by the closure of a liimt switch 97 associated with the nozzle. Closure of limit switch 97 causes the solenoid 61' in the operator 110' of valve 108 to be actuated which, augmented by the spring52', effects the rapid opening of line lltlZ. When the valve N8 is fully opened limit switch 99 is caused to be actuated thereby effecting actuation of the operator for the supply valve 1% in line 98 which begins its gradual admission of fuel through this line. Check valve Ml? in line .102 prevents a backup of oil in thereturn line 102.

A schematic diagram showing the circuitry employed forthe sequenced ignition of the burners in the oil burner system is shown in FIGURE 9. Itsarrangement is generally the same as that for gas shownin FIGURE 8;

however additional lines and components have been added 7 to effect first, movement of the burner nozzle dtiinto its firing position and second, opening of the return valve 108 and finally opening of supply valve lit- 5. Lines 146 i and 148 supply the system with electric power. Across connected and, like the comparable switches in the control system for the gas burners previously described, are closed after certain prerequisites for safe burner operation have een satisfied. Switches 158 are connected to a pressure indicating device 159 at the fuel source to indicate that the oil pressure is sufficient for safe burner operation. Switches 16% are connected to individual igniter sensing devices which indicate that each igniter torch is in operation. Switches 162 are closed by means of relay 1163 upon receiving a start command from 'a computer or start switch, neither of which has been shown here. Switches 164% have been placed in each line so as to enable the burners to be selectively removed from service for maintenance purposes and must be in a closed position in order for electric power to be admitted to the burner at any one corner. Elements 94 in lines 150 are the solenoids shown in FIGURE 5 which actuate the 4-way valves to advance the burner nozzles 80. Connected in parallel with each line 15% are lines 151 in which the limit switches 97, also shown in FIGURE 5, are connected. Switches 9'? are closed once the burner nozzle 80 with which each is associated reaches its fully advanced position. Also contained in this line is a solenoid 61' which is actuated to open the oil return valve 1%. Connected in parallel with the solenoid 61' is a line that contains the limit switch Q9 which closes when the return valve 193 is fully open to operate the pump motor of the operator for supply valve 1%.

' Lines 152 contain the limit switches 62 associated with each valve 1% to indicate a full opening thereof. Connected in serieswith these switches are electro-magnetic multiplying relays 182 similar to the relays 1443 referred to in the description of the gas burner system and shown in FIGURE 11, with the exception that in these relays switches 184 shown in FIGURE 9 replace the switches 336. The multiplying relay 182 contains a plurality of contacts which have leads connecting the relay to ancillary equipment for each burner such as an indicating light on the control panel, a counting circuit to check the number of burners actually in operation and, an indicating signal to the computer to indicate that the valve is open, and several other means which are not germane to an understanding of the present invention. Additionally, relays 182A, 18215, 1820 and 182E serve to close switches 184 or 186 in the appropriate lines to establish continuity in V the circuit of the next burner to be lighted, relays 182A and E8213 actuating switches 184E and 18413 respectively and relays 182F and 182C actuating switches 186C and 186E respectively. 7 Relays 183 are similar to the relays 182, however, they contain additional contact points 1186 which serve to close switches in the circuit to thereby establish the alternate route for the actuating signals, relays 183B and 183G serving to close switches 1361-1 and 1868 respectively and relays 183E and 1531) serving to close switches 186D andiSG respectively.

The operation of the control system for each elevation of oil burners is as follows. The oil pressure sensing device senses a satisfactory pressure in the supply source and closes the switches 158 in all of the lines 156 Similarly, the igniter sensing devices associated with the various burners sense the fact that the igniter torch'jis on and closesswitches 16h inthe appropriate lines 1%. Next, the maintenance switches 164 in lines 159 must be thrown to the on position thereby establishing a closed circuit thcrethrough. Thereafter, the elevation start command is given establishing a closing of contacts 162 in the lines 156 This startycommand may originate from a signal V emitted from a computer source or may be given merely by means of an operator throwing a switch. When the contacts 162 are closed in lines 1549A and R power is applied to the nozzle advance solenoids 94 which actuate the air supply valves 92 to admit air to the cylinders 84 thereby moving the nozzles of burners A and F to their advanced position. Upon reaching its advanced position, the nozzle St? of each burner will actuate the limit switch 97 which will establish power to the relief valve solenoid 61 in return valve 108 causing it to rapidly open. When valve 108 is fully open limit switch 99 is closed thereby establishing power to the operator pump motor 55 for supply valve 106 to eifect its gradual opening.

Once the valves 1% reach the fully open position, they trip the limit switches 62 shown in FIGURE 6 associated with each of the valve stems 48 and which are interposed in lines 152A and 152F in series with the electro-magnetic multiplying relays 182A and 182R Closure of the switches 62 causes the relays 182A and 182F to be energized thereby sending signals to the various equipment to which the contacts on the relay are connected. Among the contacts closed by the relays 182A and 182F are those associated with switches 1841-1 and 186C which thereby cause an establishment of power to the burner apparatus located in corners H and C where the same ignition cycle is repeated. After these burners become ignited the cycle is again repeated with regard to the burners located in corners B and E.

Corners B and 'E have associated therewith relays 183 which (litter from the relays 182 in that they additionally contain contacts which enable them to elfect closure of switch *186H along with switch 1840. Since the burners in corners H and C have already been placed into operation by the impulse established upon the closure of switches 1 84H and 186C in each of the lines '15tlH and 156C, closure of switches 1861-1 and 186C is, in fact, superfluous. Their closure comes into play only when the parallel switch in the associated line cannot receive an actuating impulse because one of the burners ahead of it in the sequence has been rendered inoperative thus preventing the relay associated with that burner to be actuated. When this happens, the closure of the alternate switch by the appropriate relay will then initiate operation of the burner in that corner.

By means of this arrangement, the inability of one of the burners to function properly thereby preventing the relay 183 associated with that burner from operating will not prevent the other burners in that half of the burner system from being placed into operation since the operating signal will now come from a relay in the other half of the burner system. This feature was described earlier with regard to the gas burner system with reference to the schematic shown in FIGURE 3. The operation that is applied there is equally applicable to the oil burner system shown in FIGURE 9.

Assuming, for example, that the burner in corner H is prevented from operating because its igniter torch is extinguished thereby causing switch 160 in line 15611 to remain open, the remaining burners, namely B and G, that are dependent upon the operation of burner H for initiating their operation cannot receive their actuating signal from burner H. Therefore, in order to ignite these burners, which are otherwise capable of operating, the relay 183D associated with burner D when actuated closes the switch 186G in addition to switch 184E to start the ignition cycle in burner G. When this is completed, the relay 183G similarly serves to close switch 1863 in addition to 184D to ignite the burner in corner B.

The result is that all of the burners in the elevation are put in operation with exception, of course, of the burner in corner H which was incapable of being peratecl. This burner is therefore isolated from the remainder of the elevation to permit those burners which are capable of operation to be operated in spite of the presence of a defective burner in the system.

The present control system also provides a means whereby the burners in each furnace elevation can be shutdown automatically. Shutdown of a burner system I employing gas as the burning medium presents no problem due to the greater turndown ratio which is possible when gas is being burned; therefore, to shut down the gas burner system, all that is required would be an actuation of all of the gas supply valves 4% simultaneously.

However, when oil is employed as the burning medium, the shutdown must be gradual in order to overcome the problem of smoking within the furnace chamber. It is, therefore, desirable to shut down the burners of each furnace elevation gradually so that the creation of smoke within the furnace is kept to a minimum. The present system provides for such a gradual shutdown by sequencing the shutdown of the individual burners in each elevation in much the same manner as they are ignited.

FIGURE 10 shows a schematic wiring diagram of the control system for the sequence shutdown of a furnace elevation. Power lines 146 and 148 have connected thereto in parallel a pair of lines 196 and 198 for each burner arrangement. As before in the specification, each of these lines has been given an appropriate sufiix to indicate the burner with which each is associated. All of the lines 196 contain shutdown command switches 200 and the relief valve solenoid 61 of valve 40 shown in FIG- URE 6. Connected in parallel with the relief valve solenoid 61 is the return valve'actuator pump motor 55' of the return valves 16 8 and switch 294 located in series with retraction solenoid 96. Switch 2% is a limit switch associated with the return valves to indicate when the valve is fully closed. Closure of switch 204 efiects actuation of the burner nozzle retraction solenoid 96 which operates the 4-way valve 92 to retract the burner nozzle 8%. Switch 132 is located in lines 196 and, as shown in FIGURE 5, this switch is a limit switch which is closed when the burner nozzle reaches its retracted position. Closure of switch 132 eifects actuation of the relays 236. These relays 206, a detail of which is shown in FIGURE 13, are substantially the same asthose employed in the ignition circuits. They possess a plurality of contacts which are simultaneously actuated to complete circuits extending to an indicating light on the control board, the computer feedback circuit, ignitor shut down circuit and other apparatus associated with the burner. The relays 206A and 206H contain contacts 2081i and 2088 associated with lines 19$H and 1983mspectively. Likewise, relays 206F and 206C contain contacts 210C and 21GB associated with lines 198C and 138E respectively. Actuation of the relays 206 therefore cause the switches to close thereby effecting circuit completion in the lines with which the switches 208 and 210 are associated. Switches 208 and 210 are connected in parallel in all of the lines 198 other than those which are associated with each of the initiating corners of the furnace, those being'lines 198A and 198F.

The operation of the shutdown control system is substantially the same as that for the burner ignition system. The elevation receives a shutdown command either from a computer or a start switch thereby closing the switches 200 in all of the lines 198. Closure of these switches initiates the shutdown cycle of the burner apparatus located in corners A and F and readies theother burners to receive the shutdown actuating signals. When the switches 289 in lines 198A and 198F close, the relief valve solenoids 61 in the supply valves 40 associated with burners A and F are actuated thereby opening the actuator relief valves 69 in each of the supply valves thereby relieving the fluid pressure beneath the pistons St) and permitting the valves 49 to be rapidly closed by means of the springs 52. At the same time, actuation of the return valve actuator pump motors 55' associated with the valves N8 is effected thereby admitting fluid to the valve actuator cylinder 51' to gradually close the valve. When valve 163 closes, contacts 204 are made thereby actuating the solenoid 96 associated with the 4-way valve 92 to direct compressed air through line 89 and open the vent port 91 thereby effecting retraction of theburner nozzle 80. When the burner nozzle 80 reaches its fully retracted position, limit switch 132 is actuated which, in turn, actuates the relays 206A and 2661 relay 206A serving to close switch 2081-1 and relay 206F serving to close switch 2100 thereby permitting the entire cycle to l 1- be repeated in the circuits associated with burners H and C. These cycles are thereafter again repeated until all of the burners are shut down.

The relays 2MB, 2tl7G, 207D and ZGIE, a typical relay 297 being shown in FIGURE 14, contains contacts which effect closure of the appropriate switches 268 and 216i.

Closure of these switches provides means for completing the alternate circuit that conveys the shutdown signal should one of the burners malfunction which would prevent continuance of the signal over the principal routes. The alternate routing of the burner shutdown signal is identical to the alternate routing of the ignition sequence signal and is employed when one of the burners is halted on shutdown to permit shutdown of the remainder of the elevation.

It can be seen from the foregoing that the present invention provides a control system whereby the burner system of a large vapor generator can be ignited or shut down in sequenced progression by completely automatic means. system effects the actuation of each of the burner components in sequenced progression. The system described hereinabove, by avoiding the use of various independent timing mechanism but instead using for its timing the movement of the various burner components themselves, reduces the amount of equipment which must be employed in an automated burner system thereby reducing the overall cost of such a system but, in addition, increasing the degree of reliability of the system. The present system is simple and inexpensive requiring only standard components, but the arrangement described eifects a highly efficient means for sequencing the ignition and shutdown of a vapor generator burner system.

The description-set forth herein is intended to be merely illustrative of the invention and is not intended as a limitation thereof, it being understood that many and varied modifications can be made to the disclosed embodiment without departing from the spirit of the invention as defined by the appended claims.

What isclaimed is:

1. In a vapor generator having a furnace chamber, a.

burner system including a plurality of fuel burners positionedat predetermined points in said furnace chamber and burner operating means associated with each of said burners, a burner sequencing control system including means for simultaneously imparting actuating signals to the operating means of a pair of burners in said burner system, means for advancing the actuating signals from said previously actuated burner operating means to the remaining burner operating means in paired sequenced progression, each of said signals being adapted to actuate the operating means of half of the burners in said system, and means for effecting actuation of all of the remaining operative burner operating means by one of said actuating signals upon cessation of the progression of the other actuating signal.

2. In combination with a vapor generator having a furnace chamber and a burner system including a plurality of fuel burners positioned at spaced points in said furnace chamber and burner operating means associated with each of said burners, a burner sequencing control system including means for simultaneously imparting actuating signals to the operating meansof two of said burners, means foradvancing the actuating signals from both of said previously actuated burner operating means to the operating means of the remaining burners in said burner system in sequence progression, each of said signals being adapted to actuate the operating means of half the'bur ners in said burner system, and means for effecting actuation of all of the remaining operative burner operating means by one of: said actuating signals upon cessation of the progression of the other actuating signal.

3. In combination with a vapor generator having a furnace chamber comprising dual furnace cavities, a

The mere admission of an initiating signal to the oneness burner system including a plurality of fuel burners positioned at spaced points in each of said furnace cavities, each of said burners having individual burner operating means associated therewith and a burner sequencing control system including means for simultaneously imparting actuating signals to the operating means of one burner in each of said furnace cavities, means for normally advancing said actuating signals from each of said previously actuated burner operating means to the operating means of the remaining burners in said burner system in sequence progression, each of said signals being normally adapted to actuate the operating means of half the burners in said burner system in a progression whereby the operating means of burners in alternate cavities are actuated, and means for effecting actuation of all of the remaining operative burner operating means by one of said actuating signals upon cessation of the progression of the other actuating signal.

' 4. In a vaporv generator having a burner system including a plurality of fuel burners, a fuel supply source, fuel lines connecting said burners to said fuel supply source, valves interposed in said lines between said sup ply source and said burners, and valve operating means imparting gradual operation to said valves, a burner sequencing control system comprising switch means associated with each of said valves, said switch means beingactuated when said valves achieves an operable position, first signal conveying means connecting said switches to a posteriorly operated valve operating means in the progressive sequence, second signal conveying means connecting saidf switches to an anteriorly operated valve operating means in the progressive sequence, and means imparting actuating signals to the operating means of the first and last valves in the progressive'sequence such that the actuatingv signals traverse the burner system in both the progressive and regressive directions.

5. In combination with a vapor generator having a furnace chamber comprising dual furnace cavities and a burner system including a plurality of fuel burners positioned at spaced points in each of said furnace cavities, a fuel supply source, fuel lines connecting said burners to said fuel supply source, valves interposed in said lines between said supply source and said burners and valve operating means effecting gradual operation of said valves, a burner sequencing control system comprising switch means associated with each of said valves, said switch means being actuated when said valves achieve a predetermined position, first signal conveying means connecting said switches to a posterio rly operated valve operating means in the progressive sequence, second signal conveying means connecting said switches to an anteriorly operated valve operating means in the progressive direction of said burner sequence, said first and second signal conveying means connecting the valves and operating means of the burners in alternate furnace cavities, and means imparting actuating signals to the operating means of'the first and last valves in a progressive sequence such that actuating signals traverse the burner system in both the progressive and regressive directions actuating the operating means of burnersin alternate furnace cavities in succession.

6. A vapor generator comprising a furnace chamber, a plurality of oil fired burners positioned at spaced points in said furnace chamber, an oil supply source, lines conmeeting said burners to said oil supply source, supply valves interposed in said lines between said supply source and. said burners, supply valve operating means associated witheach of said supply valves for effecting the 'posteriorly operated supply valve in a progressive direction of burner sequence, second signal conveying means connecting said switch to the operating means of an anteriorly operated supply valve in a progressive direction of burner sequence, and means simultaneously imparting actuating signals to the operating means of the first and last supply valves at the progressive sequence such that actuating signals traverse the burner system in both the progressive and regressive directions.

7. In combination with a vapor generator having a furnace chamber and a burner system comprising a plurality of fuel burners positioned at spaced points about said furnace chamber, a fuel source, fuel lines connecting said burners to said fuel source, supply valves interposed in said fuel lines, operating means associated with said valves for imparting thereto the characteristic of gradual opening; a control system for igniting said burners in sequence including means for preventing the admission of fuel to any of said burners which are incapable of operation and means for actuating the supply valve operating means of the operable burners when other of said operable burner supply valves have reached a full open position.

8. In combination with a vapor generator having a furnace chamber and a burner system comprising a plurality of fuel burners positioned at spaced points about said furnace chamber, a fuel source, fuel lines connecting said burners to said fuel source, supply valves interposed in said fuel lines, operating means associated with said valves for imparting thereto the characteristic of gradual opening; a control system for igniting said burners in sequence including electrical circuit means wherein the control lines for each of said burners are connected in parallel and arranged for operation of said burners in a predetermined order, one of said control lines for each of said burners including a plurality of parallely connected switches which are adapted to be actuated when the burner with which they are associated is operable and motor means driving said supply valve operating means connected in series with said switches and adapted to be operated when all of said switches have been actuated; the other of said control lines for each of said burners including a limit switch which is actuated when the supply valve with which it is associated reaches a full open position and a relay having a coil connected in series with said limit switch which is actuated upon actuation of said limit switch, said relay coil being operable to actuate a switch in the said one control line of another of said burners having a posterior position in said predetermined order.

9. In combination with a vapor generator having a furnace chamber and a burner system comprising a plurality of fuel burners positioned at spaced points about said furnace chamber, a fuel source, fuel lines connecting said burners to said fuel source, supply valves interposed in said fuel lines, operating means associated with said valves for imparting thereto the characteristic of gradual opening; a control system for igniting said burners in sequence including electrical circuit means wherein the control lines for each of said burners are connected in parallel and arranged for operation of said burners in a predetermined order, one of said control lines for each of said burners including a plurality of serially connected switches which are adapted to be actuated when the burner with which they are associated is operable and motor means driving said supply valve operating means connected in series with said switches and adapted to be operated when all of said switches have been actuated; the other of said control lines for each of said burners including a limit switch which is actuated when the supply valve with which it is associated reaches a full open position and a relay having a coil connected in series with said limit switch, said relay coil being actuated upon actuation of said limit switch and being operable to actuate a switch in the said one control line of another of said burners having a posterior position in said predetermined order, the relay associated with some of said burners being additionally adapted to actuate a switch in the said one control line of another of said burners having an anterior position in said predetermined order.

10. In a vapor generator having a furnace chamber, a burner system including a plurality of fuel burners positioned at predetermined points in said furnace chamber and burner operating means associated with each of said burners, a burner sequencingcontrol system including means for simultaneously imparting actuating signals to the operating means of a pair of burners in said burner system, means for advancing the actuating signals from said previously actuated burner operating means to the remaining burner operating means in paired sequenced progression, each of said signals being adapted to actuate the operating means of half of the burners in said system.

References Cited by the Examiner UNITED STATES PATENTS 2,362,045 11/44 Bliss. 2,622,669 12/52 Caracristi et al. 158-28 3,049,168 8/62 Litvinoif l5836 JAMES W. WESTHAVER, Primary Examiner. 

1. IN A VAPOR GENERATOR HAVING A FURNACE CHAMBER, A BURNER SYSTEM INCLUDING A PLURALITY OF FUEL BURNERS POSITIONED AT PREDTERMINED POINTS IN SAID FURNACE CHAMBER AND BURNER OPERATING MEANS ASSOCIATED WITH EACH OF SAID BURNERS, A BURNER SEQUENCING CONTROL SYSTEM INCLUDING MEANS FOR SIMULTANEOUSLY IMPARTING ACTUTING SIGNALS TO THE OPERATING MEANS OF A PAIR OF BURNERS IN SAID BURNER SYSTEM, MEANS FOR ADVANCING THE ACTUATING SIGNALS FROM SAID PREVIOUSLY ACTUATED BURNER OPERATING MEANS TO THE REMAINING BURNER OPERATING MEANS IN PAIRED SEQUENCED PROGRESSION, EACH OF SAID SIGNALS BEING ADAPTED TO ACTUATE THE OPERATING MEANS OF HALF OF THE BURNERS IN SAID 